cold start up idle problem

SON240sx Automotive
1

I have a problem with my idle when i start my car up in the morning after its been sitting for a while. Usually when the engine is cold it will idle around 1300rpm until it warms up, but with my car it doesn’t do that. When i start my car the rpm’s dont even climb over 1000 and they just get lower and lower and sometimes the car even stalls. When it doesnt stall, the rpms will drop to about 400-500 and then will slowly start to climb again but still dont go to above 1000 rpm like they should when the engine is cold. I checked sensors like the MAF, coolant temp, TPS, and idle motor and they are all fine.
what could it be??

this is a 1990 KA24E by the way.

thanks

2

Sound like the AAC (?) valve… the one hidden under the intake manifold.

-Martin.

3

same problem what is the AAC valve and how can it be fixed?